The present invention relates to integrated circuit packaging, and more particularly to an improved process for fabricating a Land Grid Array (LGA) packaged device.
An integrated circuit (IC) die is a small device formed as part of a semiconductor wafer, such as a silicon wafer. A leadframe is a metal frame that usually includes a paddle that supports the IC die that has been cut from the wafer. The leadframe also has lead fingers that provide external electrical connections. That is, the die is attached to the die paddle and then bonding pads of the die are connected to the lead fingers via wire bonding or flip chip bumping to provide the external electrical connections. Encapsulating the die and wire bonds or flip chip bumps with a protective material forms a package. Depending on the package type, the external electrical connections may be used as-is, such as in a Thin Small Outline Package (TSOP), or further processed, such as by attaching spherical solder balls for a Ball Grid Array (BGA). These terminal points allow the die to be electrically connected with other circuits, such as on a printed circuit board. However, it can be expensive and time-consuming to form a leadframe and package a device if steps like chemical etching and etch back are required.
Virtually all electronic devices use packaged ICs and with the ever present demand for smaller yet more powerful devices, a decrease in the package size is highly desirable. LGA packages offer reduced height by eliminating the solder balls that are part of a ball grid array (BGA) package. Instead of attaching the packaged device to a printed circuit board (PCB) with solder balls, LGA packages are attached to the PCB via a socket. More recently, LGA packages have been reflow-mounted using solder that has been applied to the board. The reduced package height without a decrease in reliability is making LGA packages popular for many electronic devices, such as cellular telephones, digital cameras, personal digital assistants (PDA), etc. Further, LGA packages are able to achieve higher pin counts with smaller packages. At the same time, the electrical path from the IC to the package pad is shortened.
Thus, it is desirable to have a method of decreasing the size of packaged ICs. It is also desirable to provide an inexpensive method of packaging ICs.